Conventionally, lens driving devices for driving lenses have been provided in optical devices. For example, optical pickups may be provided with lens driving devices for driving a movable lens, such as a collimating lens, along the direction of the optical axis for the purpose of suppressing the effect of spherical aberration. Such a lens driving device is structured through the provision of, for example, a lens holder for holding the lens, a driving portion for applying a driving force to the lens holder, and a guide shaft for guiding the lens holder so as to move in the target direction. The driving portion may use a motor of a rotating type, such as a stepping motor, or may use a linear motor mechanism.
Patent Citation 1, for example, discloses a lens driving device that uses a linear motor mechanism. This Patent Citation 1 discloses the superimposition of an AC voltage on a DC voltage and the application of the voltage to a coil, when driving a lens holder, for the purpose of reducing the frictional force between the lens holder (a movable portion) and the guide shaft.